THE PRINCETON CO.

What it is: A treatment that helps to restore scalp imbalances, relieve irritation and revitalize hair.

What it does: This concentrated, lightweight formula features antioxidant-rich argan oil as well as geranium and lavender essential oils to nourish and soothe the scalp. Salicylic acid provides mild exfoliation to help minimize flakiness.

How to use: Divide your hair into sections and apply 3–6 drops of treatment to each one. Massage into your scalp and leave on for 5–10 minutes. Comb through, then rinse. Follow with shampoo and conditioner. Use weekly to start and less frequently as condition improves.